I recommend a supermotard. Shit tons of fun at regular (mostly) non lethal speeds. Easy to ride, backs around corners by itself, and when you do go down, you'll probably be going under 100kmh. If you like to crap your drawers with speed, then some type of crotch rocket, but it's not as much fun and when you come off the bike you'll be surprised when your body goes through the hydro pole at 200kmh. Sorry, several friends have died getting on bikes too fast too soon. Maybe get your first dumps in on the enduro, then when your done scratching and denting things, get what you want. After riding a motorcycle for about 2 years, I considered myself lucky and realized what I noob I had been. A couple of friends who got really nice bikes right off the bat are now dead from that first learning time. Take it easy, motorcycling is a blast.
My first was a 1980 Kawasaki KZ 650,in 1991, what a piece that was. I have waaaaay more fun on my DRZ400 than on any bike so far. I found the big cruisers very uncomfortable for long rides, and where are your balls supposed to go with the tank on those crotch rockets anyway?